Method of and means for charging terminal potheads with insulating material



Get. 31, A |y H sofq, METHOD OF AND MEANS FOR CHARGING TERMINAL POTHEADSWITH INSULATING MATERIAL Filed Aug. 14, 1950 2 Sheets-Sheet l r WiINVENTOR ALFRED MORRIS THOMSON ATTORNEYS Oct. 31, 1933. A, M. THOMSON1,932,493

METHOD OF AND MEANS FOR CHARGING TERMINAL POTHEADS WITH INSULATINGMATERIAL Filed Aug. 14, 1930 2 Sheets-Sheet 2 ENVENTOR ALFRED MORRISTHOMSON iwab w;

ATTORNEY3 Ill Patented Oct. 31, 1933 METHOD OF AND MEANS FOR CHARGINGTERIVIINAL POTHEADS WITH INSULATING MATERIAL Alfred Morris Thomson,Newark, N. J., assignor to Dardelet Threadlock Corporation, New York, N.Y., a corporation of Delaware Application August 14, 1930. Serial No.475,323

8 Claims.

Important objects of the present invention are to provide an electricalconnecting and insulating device, known as a terminal pothead filledwith improved molded insulation free from air spaces or bubbles to moreeffectually insulate the enclosed electrical conductors; to provide'forthe charging of such a device with insulating material in a molten statewhile effectually excluding air and thereby prevent air spaces in theinsulation; to provide for the exhaustion of air from the casing of thedevice preparatory to receiving the charge of molten material and alsoprevent the entrance of air along with the molten material; to preventthe escape of the molten material through the air exhausting connection;and to provide a satisfactory apparatus for attaining these ends.

In the drawings,

Fig. 1 is'a side View of a pothead connected with means for exhaustingair from its casing and means for charging the casing with molteninsulation;

Fig. 2 a fragmentary side view of the pothead partly in section, upon alarger scale, and showing the first stage of the charging or pouringoperation;

Fig. 3 a detail section takenon the line 3-3 of Fig. 2;

Fig. 4 a sectional View of the pothead fully charged with the molteninsulating material; and

Fig. 5 a fragmentary sectional view of the charged pothead with its airexhaustion port and its charging" port closed.

The pothead structure includes a cast iron casing or bell 1 of elbowform, having two open ends at right angles to each other, and enlargedat one end. At one side said casing is formed with brackets 2 forattachment to a support. The larger end of the casing is directed upwardin the present instance and is closed by a cap 3. A gasket 4 isinterposed between said cap and the casing end and a depending flange 5formed on the cap surrounds the gasket and a narrow edge flange formedon the casing. Cap screws 6 are passed through ears 7 formed on the capand are threaded into ears 8 formed upon the casing, to detachably holdthe cap in place and clamped against the gasket.

Mounted upon the cap 3are a plurality of tubular porcelain insulators 9.In the present instance there are three insulators, and, for supportingthem, the cap is formed with bosses 10 each having a threadedapertureopening into the interior of the casing. A threaded ring orsleeve 11 of drawn brass is screwed into the aperture of each boss andis formed with a flange abutting the outer end of the boss. Theinsulator supported by each boss has its lower end extending throughsleeve 11 and into the casing and an abutment flange is formed on theinsulator and bears against said flange of the sleeve. Between thesleeve and the inserted end of the insulator there is an annular spacewhich is filled with cement 12. Thereby the insulators are rigidly heldto the cap 3 and their connections with the latter are closed and sealedairtight. Each insulator is formed with a plurality of encirclingflanges or skirts formed to shed water.

The electrical conductors or cables designated 13, lead to the casingthrough a pipe '14, preferably of galvanized iron, and enter the smallerend of the casing. Pipe 14 is joined to the casing end through themedium of a connecting sleeve 15. The latter is formed around one endwith a flat outwardly extending flange 16 which is opposed to a flatinwardly extending flange 17 formed on the casing end. A gasket 18,preferably of vellumoid, is interposed between said opposed flanges andthe latter are clamped against the gasket by cap screws 19. The oppositeend of the connector sleeve is cup shaped to receive the pipe and has athreaded connection 20 therewith. The conductors 13 are individuallysheathed with insulation and the group of conductors is wrapped withsuitable insulation 52 and enclosed by a tubular sheathing 21 of leadwhich extends through the pipe 14 and the sleeve 15 and into the casing.Said tube is drawn and compressed about the enclosed insulatedconductors so that the latter have an airtight fit within the tube. Atits flanged end the sleeve 15 is formed with a threaded recesssurrounding the tube 21 and having a threaded brass packing gland 22screwed into it and encircling the tube. The inner end of the gland andthe opposed inner end of the recess are oppositely tapered and having apacking 23, preferably of lead wool, interposed between them. Saidpacking is compressed about the insulated tube by screwingthe gland, anda closely sealed airtight joint is formed.

The insulation 52 and lead sheathing 21 terminate just within the casing1, and the conductors 13 separate at this point, said conductors eachleading into the bore of one of the insulators 9 and fitting, at its endinto a socket formed upon a terminal rod 24 and being soldered therein.The terminal rod extends outward from the upper end of theinsulator andis threaded. A hood nut 25, preferably of cast brass, is screwed uponthe &

projecting end of the rod and covers it. Interposed between the end ofthe insulator and the hood nut is a gasket 26, preferably of vellumoid,and the nut is formed with a flange surrounding the gashet. an aeriallug 2'1, preferably of cast copper, [or the attachment of an outsideconductor 51, is clamped upon the hood nut.

The bore of the insulator is materially larger than the diameter of theconductor and that of the terminal rod and provides a surrounding spacefor the insulation. This space, together with the interior of thecasing, is filled with the insulating material 23 in a manner to bedescribed hereinafter. At its outer end, the bore is reduced for a shortdistance and, at the inner end of the reduced portion, two diametricallyopposite notches 29 are formed. A locking pin 30 is passed through theterminal rod 24 and engages in said notches to prevent the rod fromturning.

The invention provides for the charging of the casing '1 and theassembled insulators with molten in a manner to prevent air spaces orbubbles in the insulation and obtain a uniform density thereof and acomplete filling of the dosing and insulators around the electricalconduits. This is accomplished by exhausting the air from the pothead toproduce an almost perfect vacuum, maintaining the vacuum while themolten insulation is poured, and preventing the illifilroduction of airalong with the molten mater The cap '3, at points located at oppositesides of the insulators, is formed with two upwardly projecting nipples31 which are externally threaded and open into the interior of thecasing 1. Each nipple is normally closed by a threaded cap 32 and gasket33, and when the air is to be exhausted from the pothead preparatory tocharging it with molten insulation the cap and gasket are removed fromone of the nipples and a suction pump 34 detachably connected thereto.This pump may be of a simple hand operated type. Its connection with thenipple is made through the medium of an elbow 35, a threaded connectorsleeve 36 coupling the elbow to the pump and a threaded connector sleeve37 coupling the elbow to the threaded nipple. Sleeve 37 is provided withan inwardly extending abutment flange 38 which engages an outwardlyextending flange 39 formed on one end of the elbow. Interposed betweensaid flanged end of the elbow and the end of the nipple is a disk 40which is formed of material pervious to air but not pervious to a fluidhaving the consistency of themolten insulation,

and not fusible or destructible by said molten insulation or heattransferred therefrom. Preferabiy the material of the disk is a hard,porous one, suchas pumice stone or unglazed porcelain.

The sleeve 3'? is tightened to clamp the disk against the nipple andfirmly hold the elbow. The provision of two nipples enables the pump tobe connected to either side of the pothead, according to the convenienceof the workman and the clearance for the pump.

For the introduction of the molten insulation, the casing 1 is formed atone side thereof with an outwardly extending nipple 41, externallythreaded and opening into the interior of the casing.

.. Niirmauy this nipple is closed by a threaded cap 42 and a gasket 50.When the molten insulation is to be poured, cap 42 and gasket 50 areremoved ind a supply pipe 43 is connected to the nipple. This pipe leadsdownwardly to the nipple from a point elevated above the tops of theinsulators b, and is provided at its upper end with a funnel or hopper44. The pipe is connected to the nipple 41 through the medium of athreaded connector sleeve 45. The latter is screwed upon the nipple andis formed with an inwardly extending flange 46 to engage an outwardlyextending flange 4'7 upon the pipe. Interposed and clamped between theflanged end of the pipe and the opposed end of the nipple is a disk 48entirely obstructing the entrance to the nipple. This disk is formed ofa hard dense material which is capable of excluding air and of beingfused by contact with the molten insulating material. Preferably thelatter material is a suitable grade of bitumen and the disk is made ofsolidified bitumen which is fusible at the same temperature as theinsulating material.

The pump is first operated to exhaust the air from the pothead throughthe porous disk 40. This, in addition to preparing the pothead toreceive the insulation, serves to test the various Joints for leakage.When the joints are effectually sealed, an almost perfect vacuum may beproduced. A gauge 49 may be connected to the pump to indicate thevacuum. The molten bitumen is poured into the hopper 44, whose capacityis preferably at least equal to the pothead space which is to be filled,after a. vacuum or substantial vacuum is produced in the casing. Fromthe hopper, which is elevated sufliciently to provide a good head, themolten bitumen flows down the supply pipe 43 to the disk 43. The latterobstructs the flow so that the molten material is dammed up in the pipe43, to completely fill the cross section thereof and exclude air. Theobstruction of the flow, however, lasts for only a short period as thehot molten bitumen melts away the solidified bitumen disk and opens apassage to the interior of the pothead. Operation of the suction pumpmay be continued during the introduction of the molten bitumen, any airwithin the casing and hollow insulators passing out through the porousdisk 40. The bitumen is thus free to flow in and completely fill thespaces within the casing l, the cap 3, the insulators 9 and the nipples31 and 41. It is prevented from passing through the pump connection bythe disk 40. Exhaustion of the air from the pothead and exclusion of airfrom the entering stream of molten insulation causes the latter tocompletely fill all of the spaces in the pothead, and when theinsulation solidifies it will be uniformly dense and free from airbubbles, spaces or pores. The surrounded conductors within the potheadwill therefore be thoroughly insulated and short circulting to the metalparts of the pothead will be prevented.

After the charging of the pothead and solidifying of the bitumen, thenipples 31 and 41 are capped, as shown in Fig. 5, the charging means andvacuum creating means being first disconnected from said nipples.

What I claim is:

1. The method of filling free space within an encased joint of anelectricity conductor with insulating material in a liquid state whichcomprises maintaining a suction outlet in said casing closed to passageof said insulating material but open to passage of gaseous materialduring filling of said space, and admitting said insulating materialinto the space and subjecting it to suction at said outlet until thespace is filled with bubble-free insulating material.

2. The method of charging the free casing space in an encased joint ofan electricity condoctor with normally solid insulating material,

which comprises flowing said material in a molten state in a stream tothe casing, fusing an entrance for said stream into said casing throughthe medium of the hot leading end of the stream, and permitting thestream of molten material to flow into the casing through the entrancethus opened.

3. The method of charging with normally solid insulating material thefree casing space within an encased joint of an electricity conductor,which comprises heating a supply of said material to a molten state,flowing a stream of said molten material from below the surface of saidsupply to the joint casing, melting open an inlet in the casing for thestream by the hot lead ing end of the stream, allowing the said streamof molten maaterial to continue to flow from said supply into the casingthrough the inlet thus opened, restraining the admitted material frombeing sucked out of the casing, subjecting the interior of the casingand the restrained material to suction during said continued flow of thematerial into the casing until the free space of the casing is filledwith bubble-free molten insulating material, and then allowing theinsulating material in said space to cool and solidify.

4. The method of filling the free space in an encased joint of anelectricity conductor with normally solid insulating material, whichcomprises keeping the free space open to a supply of said insulatingmaterial in a molten state and closed to inflow of free air; and, whileso doing, subjecting the free space to suction and keeping itcontinually closed to outflow of the molten insulating material until nomore of the insulating material can flow into said space from thesupply.

5. The method of charging the free space in an encased joint of anelectricty conductor with insulating material in a liquid state, whichcomprises keeping said space open to a head of said liquid insulatingmaterial which bars inflow of free air into the space, andsimultaneously subjecting the space to suction and the fed material to ascreening action at an air outlet from said casing to retain in thecasing all the liquid material fed thereinto and exhaust air from thecasing until the casing is filled with bubble-free liquid insulatingmaterial.

6. The method of charging the free space of an encased joint of anelectricity conductor with molten insulating material, which comprisescontinuously charging said molten material into said space while bothexhausting said space through a gas outlet and filtering the moltenmaterial from occluded gaseous material at said gas outlet until no moreof the molten material can enter said space, and thereupon allowing thegasfree filling of molten material in said space to solidify.

7. The method of filling the free space of an encased joint of anelectricity conductor with molten insulating material, which comprisesflowing said molten material in a stream from a source of supply to saidencased joint, fusing an entrance for the stream to said space throughthe medium of the hot leading end of said stream, maintaining saidstream in suflicient volume to keep said entrance closed to inflow offree air, and exhausting air from said space through an outlet whilekeeping said outlet constantly closed to outflow of the molten materialuntil no more of the molten material can flow into said space throughsaid entrance, and thereupon shutting oif said source of supply ofmolten material from the encased joint and stopping the air exhaustingaction on said space.

8. The method, as claimed in claim 7, of filling the free space of anencased joint of an electricity conductor with molten material,characterized by the step of exhausting air from the free space of saidencased joint through said outlet prior to the fusing of the entrance tosaid space for said stream of molten material.

ALFRED MORRIS THOMSON.

